O2 could be produced by abiotic means, the source isn’t necessarily life. It could be, but it’s probably not. Looking for life isn’t as simple as finding oxygen, otherwise it would be way too easy, there’s a bunch of other biosignatures and signs of habitability to look for.
A quick search shows that there’s many studies on abiotic ways to produce O2 in terrestrial planet. From good sources too, not just your random Joe. Hence, we need to look at other factors too, not just oxygen.
O2 could be produced by abiotic means, the source isn’t necessarily life. It could be, but it’s probably not. Looking for life isn’t as simple as finding oxygen, otherwise it would be way too easy, there’s a bunch of other biosignatures and signs of habitability to look for.
Except o2 is only produced in volume by a nova. Which isn’t happening on a planet.
A quick search shows that there’s many studies on abiotic ways to produce O2 in terrestrial planet. From good sources too, not just your random Joe. Hence, we need to look at other factors too, not just oxygen.